deploy/scripts/rotate-snapshots.sh creates daily-YYYY-MM-DD
snapshot + prunes daily-* older than RETAIN_DAYS. Only touches
its own daily-* namespace so hand-created snapshots (release
anchors etc) never get reaped.
02:00 timer runs ahead of the 03:15 ref-sweep + 03:30 gc so
tonight's fresh snapshot pins protect its blobs from eviction.
DRY_RUN=1 for preview.
